d303122eab
Coverity complained that simple8b_encode() might read beyond the end of the 'diffs' array, in the loop to encode the integers. That was a false positive, because we never get into the loop in modes 0 or 1, and the array is large enough for all the other modes. But I admit it's very subtle, so it's not surprising that Coverity didn't see it, and it's not very obvious to humans either. Refactor it, so that the second loop re-computes the differences, instead of carrying them over from the first loop in the 'diffs' array. This way, the 'diffs' array is not needed anymore. It makes no measurable difference in performance, and seems more straightforward this way. Also, improve the comments in simple8b_encode(): fix the comment about its return value that was flat-out wrong, and explain the condition when it returns EMPTY_CODEWORD better. In the passing, move the 'selector' from the codeword's low bits to the high bits. It doesn't matter much, but looking at the original paper, and googling around for other Simple-8b implementations, that's how it's usually done. Per Coverity, and Tom Lane's report off-list.
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